Although anisometropic amblyopia is a frequent cause of functional amblyopia in the human population, very little effort has been devoted to the development of a primate model of anisometropic amblyopia. In the proposed study, an anisometropia will be optically induced in rhesus monkeys during the critical period of visual system development by securing a negative-powered spherical lens in front of one eye. Psychophysical techniques will be used to evaluate the effects of the induced anisometropia on the monkeys' spatial resolving capacity, binocular interactions for threshold and suprathreshold stimuli, temporal and spatial integration capabilities and increment threshold spectral sensitivity functions. To determine the adequacy of the lens-reared monkey as a model for anisometropic amblyopia, performance with the treated eye will be contrasted to results obtained for the untreated eyes and compared to currently available data for human anisometropic amblyopes. Single unit neurophysiological techniques will be employed to study the response characteristics of neurons in the striate cortex with special emphasis placed on the determination of ocular dominance and the spatial resolving capacity of individual cortical neurons.